If you're curious about Keynote prototyping, Travis Isaacs' describes how he works with the presentation software to produce click-through prototypes. As Travis notes, it's even useful to people who like to go between a low-fidelity wireframe created in another application to interactive demonstrations.

You can purchase Travis' Keynote Wireframe Toolkit here on Konigi.

http://konigi.com/store/product/keynote-wireframe-toolkit